Glossary contains the abbreviations, acronyms, and some other terms used throughout the API documentation.


Access Control List. The list of Access Control Rule objects and policy statements to determine if an action will be allowed or rejected. Refer to the Access Control List object for more information.
Access Control Rule. The criteria that can be applied to calls and SMS to form the building blocks of CarrierX access control policies. Refer to the Access Control Rule object for more information.
Answering Machine Detection. A special technology which allows the system to detect if the calling party uses an automated call. CarrierX FlexML allows you to determine whether the calling party is a human or an automated call before the it answers the call or redirects to the correct destination.
Application Detail Record. The detailed records for the applications used with CarrierX. These include the detailed records for Conference Meetings and Mediator Call Detail Records.
Autonomous System Number. A unique number assigned to an autonomous system (AS) by the Internet Assigned Numbers Authority (IANA). An AS consists of blocks of IP addresses which have a distinctly defined policy for accessing external networks and are administered by a single organization but may be made up of several operators.


Call Detail Record. The detailed records for the calls. Refer to the Call Detail Record object for more information.
Carrier Identification Code. Identifies long distance carriers. When dialing a long distance call, consumers can force the call to be to routed to a specific carrier by prefixing the phone number with 101XXXX, where XXXX is a carrier’s CIC. For example, if the carrier’s CIC is 0123, then the prefix would be 1010123.
Common Language Location Identifier. Is used within the North American telecommunications industry to specify the location and function of telecommunications equipment or of a relevant location. The identifier normally consists of 11 characters. The first six characters of a CLLI code represent the place the code refers to and contain two code elements: four letters that denote the city and two letters that denote the state or similar geopolitical entity. The last five characters depend on the CLLI type and can represent a building, a non-building location, or a client site.
Caller Name Delivery. A supplementary service that is used in telephone networks to provide name identification of the calling party. The CNAM information is most often displayed in Caller ID. Is a synonym of CNAP.
Caller Name Presentation. A supplementary service that is used in telephone networks to provide name identification of the calling party. The CNAM information is most often displayed in Caller ID. Is a synonym of CNAM.
Communications Platform as a Service. A cloud-based platform that enables developers to add real-time communications features to their own applications without the need to build backend infrastructure and interfaces. CarrierX allows the developers to build their own communication applications interacting with CarrierX API.


Direct Inward Dialing Number. Phone numbers rentable through the CarrierX API or via the CarrierX portal. Refer to the Phone Numbers section of the CarrierX Core API for more information.
Detail Record. The detailed records for the applications, calls, or messages.
Digital Signal Processing/Digital Signal Processor. The use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations.
Dual-Tone Multi-Frequency. A telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF is also known in the UK as MF4. Generally speaking, it is the signal that is generated when a user presses an ordinary telephone’s touch keys.


An international standard that defines a numbering plan for the worldwide public switched telephone network and some other data networks. The phone numbers in the E.164 format must contain only digits (15 digits maximum, which can be prefixed by the + sign) split as follows:
  • Country code (1 to 3 digits)
  • Subscriber number (max 12 digits)
Early Media
The media that is sent before the call is answered. It can be system tones, announcements, or any other sound that the phone company or a person who uses FlexML PreAnswer verb wants to send you.


Home Location Register. A database that contains various information about all of the mobile subscribers authorized to use a mobile network. This information includes mobile numbers, services, whether the numbers have been ported to another network, and other similar information.


ISO 3166-1 alpha-2
Two-letter country codes defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest. E.g., US (for the United States), CA (for Canada), GB (for the United Kingdom).
ISO 3166-1 alpha-3
Three-letter country codes defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest. E.g., USA (for the United States), CAN (for Canada), GBR (for the United Kingdom).
Internet Telephony Service Providers. An Internet service provider that supplies digital telecommunication service based on Voice over Internet Protocol (VoIP) provisioned via the Internet. ITSPs provide direct Internet to users or other wholesale suppliers that consequently provide Internet to home users.


Least-Cost Routing. The process of selecting the path for outbound communications traffic routing based on the lowest available cost for a given route.
Local Number Portability. Enables end users to keep their telephone number when switching from one telecommunications service provider to another. Prior to the introduction of LNP, changing service providers meant having to get a new telephone number. LNP changed that, making it possible for consumers to retain the same telephone number. See also NP.
Location (Local) Routing Number. A ten-digit number following the specifications of the North American Numbering Plan. The LRN is stored in a database called a Service Control Point (SCP) that identifies a switching port for a local telephone exchange. The LRN is used for local number portability.


Mobile Country Code. Consists of three decimal digits, the first digit identifies the geographic region as follows (the digits 1 and 8 are not used):
  • 0: Test networks
  • 2: Europe
  • 3: North America and the Caribbean
  • 4: Asia and the Middle East
  • 5: Australia and Oceania
  • 6: Africa
  • 7: South and Central America
  • 9: Worldwide (Satellite, Air—aboard aircraft, Maritime—aboard ships, Antarctica)

MCC is used in combination with an MNC.

Mobile Network Code. Is used to uniquely identify the mobile network to the user on the mobile device display when it is connected to the network. Consists of two or three decimal digits.


North American Numbering Plan. Is a telephone numbering plan for World Zone 1. Member countries are assigned three-digit area codes under the common country 1 prefix, shown in the +1 XXX format. The North American Numbering Plan includes Canada, United States, including US territories, and many, but not all, Caribbean nations and some Caribbean Dutch and British Overseas Territories.
Number portability. Allows telephony subscribers to keep their telephone numbers when they change service provider (service provider portability), move to a new location (location portability), or change the subscribed services (service portability). See also LNP.
Numbering Plan Area. Territorial division of areas included into the North American Numbering Plan (NANP). Each territory is assigned a three-digit telephone number prefix, commonly called the area code.
The first six digits of a NANP telephone number (or of an LRN). The NPA-NXX is the PSTN address of the switch serving the telephone number.
Number Portability Administration Center. Administers the routing of telephone calls and text messages (SMS) for the telecommunications industry and its customers. As such, it facilitates local number portability in the United States and Canada. The NPAC is the telecom industry’s common, authoritative database used for routing, rating and billing calls for telephone numbers that are no longer assigned to the original NPA-NXX code holder.
Number Portability Database. The database that contains the correct routing information for all ported and pooled numbers. Is used to support the ability of a customer, either an individual or business, to take their telephone number with them (to “port” their number) if they change one mobile network carrier to another.
Number Portability Database Dip Indicator. Indicates that a query to the Number Portability Database has been made, and that the call should be routed using the phone number in the rn field (if present) instead of the original called number. Refer to the Transformations section for more information.


Operating Company Number. The identification number of the operating company to which the phone number belongs.


P-Asserted-Identity. The P-Asserted-Identity header contains the caller ID information for the call on the INVITE SIP packet. This is an acceptable way to specify privacy information for calls.
Private Branch eXchange. A telephone system within a company or organization that switches calls between users on local lines, while enabling all users to share a certain number of external phone lines. This phone system manages incoming and outgoing phone calls as well as an organization’s internal communications.
Public Switched Telephone Network. The world’s collection of interconnected voice-oriented public telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication.


Routing Number. The number that is used for the call routing. See LRN.
Remote-Party-ID. An extension to SIP that allows the calling and called party to be identified by a trusted intermediary while still being able to maintain their privacy. The Remote-Party-ID header field provides the identity of the remote party. At the called party it contains the identity of the caller, and at the calling party, it contains the translated identity of the called party.
Real-Time Transport Protocol. An Internet protocol standard that specifies a way for programs to manage the real-time transmission of audio and video over IP networks.


Session Description Protocol. A format for describing multimedia communication sessions for the purposes of session announcement and session invitation. SDP is purely a format for session description—it does not incorporate a transport protocol, and it is intended to use different transport protocols as appropriate.
Secure ID. A unique identifier of an object set by the system. This ID cannot be either set or updated by a user.
Session Initiation Protocol. A signaling protocol used for initiating, maintaining, modifying, and terminating real-time sessions that include voice, video and messaging applications.
Secure SIP. Session Initiation Protocol extended with TLS (Transport Layer Security). With TLS, a secure connection between IP PBX and VoIP telephone can be established using a handshake approach.
Service Provider Identification Number. A four-digit alphanumeric value that identifies the owner of a record in the NPAC/SMS. The SPID is an NPAC account number and in most cases is drawn from the NPAC user’s operating company number.
Secure Telephony Identity Revisited/Secure Handling of Asserted information using toKENs. Defines a certificate-based solution to attest the caller identity and protect against calling numbers being spoofed and against robocalls.


Text-to-Speech. A technology that allows the users to record natural-sounding voice messages from texts. Refer to this section to learn more about CarrierX TTS API.


User Agent. A standard SIP architecture consisting of 2 components: User Agent Client (UAC) and User Agent Server (UAS).
User Agent Client. A client application in an SIP system that initiates the SIP request sent to the User Agent Server (UAS).
User Agent Server. A server application in an SIP system that listens for the incoming SIP request sent by the User Agent Client (UAC), and prompts a user or executes a program to determine responses.
Unified Communications. A business and marketing concept describing the integration of enterprise communication services such as instant messaging (chat), presence information, voice (including IP telephony), mobility features (including extension mobility and single number reach), audio, web & video conferencing, desktop sharing, data sharing, call control and speech recognition with non-real-time communication services such as unified messaging (integrated voicemail, e-mail, SMS and fax).

CarrierX provides both means to build applications with such communications abilities using its API, and ready-made unified communications solutions, such as StartMeeting and FreeConferenceCall.

Universal Service Fund. The tax imposed by the Federal Communications Commission to fund schools, libraries, and rural health care support mechanisms. Is intended to promote universal access to telecommunications services in the United States.